What Is Shift-Left Testing, and Why Is It the Next Big Thing?

What Is Shift-Left?

The journey of the software development looks like this, even today:

As you can see, testers do not get involved in the early stages of software development such as requirement gathering or the design or the development. Testing has conveniently been moved to the extreme right in the full software development cycle. The consequences of following this approach come in the form of, delaying launch dates because testing-fixing-retesting takes a lot of time when performed at the end, or compromising the quality of the software by skipping this iterative process.

What came as a suggestion to solve these setbacks is the “Shift-Left” movement, also known as test early and test often.

Why is it important to test early and test often?

Why Is It Important to Test Early and Test Often?

Pulitzer Prize-winning author and IT consultant James Martin in his study, details the emergence of bugs in each stage of the SDLC.

And the study conducted by NASA (after reviewing Boehm, Rothman and various case studies) reveal that the cost of fixing bugs rises exponentially in that later stages of software development.

In the shift-left approach, the prevention of bugs and the cost to fix them can be improved by performing testing in the early stages of SDLC. It facilitates testers to attend requirement gathering sessions, join design sessions to understand how users look at the software, work closely with developers to understand and raise questions and create ‘what if’ test scenarios while the software is being developed.

Shift-left doesn’t mean testing will not be performed at the later stages. It will happen across the SDLC, but the test cycle will be smaller and quicker since the majority of the defects are identified during the early stages. It helps to slash down the time spent on identifying defects at the later stage and costs involved with it. Shift-left enables building quality software at speed.

Types of Shift-Left Testing  

Understanding the different approaches to shift-left testing can help organizations implement this methodology more effectively. There are primarily four types of shift-left testing:  

1. Traditional Shift-Left Testing

This approach focuses on moving testing activities earlier in the development process. Testers become involved from the requirements gathering stage, providing insights and identifying potential issues before they become deeply embedded in the project. By participating in requirement discussions, design reviews, and early development phases, testers can proactively prevent defects rather than merely detecting them. 

2. Incremental Shift-Left Testing

This approach breaks down the testing process into smaller, manageable increments. Instead of waiting for a complete feature or product, testing is performed on small, developed components. Each increment goes through a complete testing cycle, allowing teams to identify and resolve issues quickly and continuously. 

3. Continuous Shift-Left Testing

Aligned with DevOps and Agile methodologies, this approach emphasizes continuous testing throughout the entire software development lifecycle. Key characteristics include: 

• Automated testing integrated into every stage of development 
• Immediate feedback loops 
• Continuous integration and continuous deployment (CI/CD) practices 
• Real-time performance and quality monitoring 

4. Model-Based Shift-Left Testing

Leveraging mathematical models and simulation techniques, this approach involves creating detailed models of the software before actual development begins. Testers and developers collaborate to develop these models, identifying potential risks, performance bottlenecks, and design flaws early in the process. This method is particularly useful in complex systems where predicting behavior is crucial.

How Do You Enable ‘Shift-Left’ at Each Stage?

Shift-left fits testing/testers into each stage of the software development. Let’s see how this test often and test early will look in action.

Requirements

All the stakeholders, including testers, must have a clear understanding of the business requirements, design and test plan. The teams will not move into the next phase unless another set of eyes examine every aspect of the requirement.

Design

As testers are now made a part of the integrated team, they can join design sessions with developers to better understand how customers are looking at the product and leverage the aligned vision of design thinking approaches. It helps to reduce anomalies in the later stages and work more efficiently with a shared vision.

Development

In shift-left, the development team should be encouraged to begin development with testability in mind. The developers can write and test unit tests for each feature they develop and sequentially write integration tests to ensure all units of code work well in integration.

Approaches like Behavior-driven development (BDD) and Test-driven development (TDD) accelerates shift-left testing. Developers use BDD approaches by writing requirements as features in an easy to understand Gherkin language and test the same. It provides transparency and quick feedback to the developers in identifying defects at the very stage it emerged.
Example of Gherkin scenario is given below.

Testing

To realize the most benefits out of shift-left, it is essential to embrace test automation as part of your testing process. As it involves testing very often, teams should pick the right test automation tools that best fit your existing infrastructure. With test automation, both development and testing team can automate the whole build that will enhance better integration between processes, improve test coverage, amplify continuous delivery, build confidence with each release.

Challenges of Shift-Left Testing 

While shift-left testing offers numerous benefits, organizations may encounter several challenges during implementation: 

1. Traditional software development teams are often siloed, with distinct boundaries between development and testing. Shifting left requires a significant cultural transformation, breaking down these silos and promoting cross-functional collaboration. Overcoming this ingrained mindset can be a substantial challenge.
2. Implementing shift-left testing demands a broader skill set from both developers and testers. Developers need to develop testing skills, while testers must enhance their technical understanding of code and development processes. This requires substantial training and continuous learning investments.
3. Adopting shift-left testing necessitates investing in appropriate testing tools, automation frameworks, and continuous integration/continuous deployment (CI/CD) pipelines. The initial setup can be complex and costly, requiring careful selection and integration of tools that align with existing infrastructure.
4. Early testing might seem counterintuitive to teams under pressure to deliver quickly. Managers and stakeholders may initially perceive shift-left testing as adding more time to the development process, despite its long-term benefits of reducing overall development time and costs. 

Best Practices for Successful Shift-Left Testing 

1. Promote collaboration between developers, testers, and stakeholders to ensure shared responsibility for quality.

2. Invest in training to equip teams with technical and testing skills.

3. Select the right test automation tools that seamlessly integrate with the development workflow.

4. Adopt testing methodologies like Test-Driven Development (TDD) and Behavior-Driven Development (BDD) to build testable code from the start.

5. Monitor and refine the strategy by analyzing defect rates and making necessary adjustments.

6. Start small and scale gradually by implementing shift-left testing in a pilot project before expanding organization-wide.

Benefits of Shift-Left Approach

• By integrating testing early in the cycle, teams can find and fix defects faster saving a lot of time and cost
• Shift-left enables teams to fail fast and fail forward
• Enhances developer’s efficiency and code stability as the developers write code with testability
• Shift-left testing promotes test automation practices allowing developers to test their code through Continuous Integration quickly
• Helps build a high-quality product and launch it within the estimated timeline
• Ability to achieve code stability translates in improved customer satisfaction

Final Word

Shift-left testing advocates shared responsibility for building high-quality software. Shift-left testing is the next big thing because it promotes a culture change in the organization moving from traditional quality assurance to the new age of quality engineering practices.
Shift-left streamlines the entire development and testing processes, and feedback loops, thereby leading to improved product quality. This brings about a positive culture change, stimulating an environment of conducive growth for everyone in the organization.

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